1. Field of the Invention
The present invention relates to a sweetener composition, and an additive agent for use as an ingredient in a sweetener composition, which can improve the body and taste of the sweetener. The present invention also relates to methods for improving the bitterness typical of some substances.
2. Brief Description of the Related Art
In recent years, high-intensity sweeteners (high sweetness sweetener) have been utilized in a wide range of foods, including diet foods. In beverages and confectioneries, which each consume an especially large amount of these sweeteners, high-intensity sweetener compositions have been used as so-called lower-calorie sweeteners, and marketed as calorie-reduced sweeteners, calorie-free sweeteners, and sugar-free sweeteners. Typical examples of these high-intensity sweeteners include aspartame (APM), sucralose, acesulfame-K (Ace-K), neotame, N—[N-[3-(3-hydroxy-4-methoxyphenyl)propyl]-α-aspartyl]-L-phenylalanine 1-methyl ester (hereinafter abbreviated as “ANS9801”), saccharin, stevia, glycyrrhizin, thaumatin, and monellin.
However, in general, consumers have become familiar over the years with the sweet taste of sugar, glucose fructose syrup, and the like, which have also been used in foods in the past, and hence do not often prefer the qualities of the sweet taste of the high-intensity artificial sweeteners as described above. For example, APM is known for its flavor-enhancing effect and its ability to reduce bitterness or astringency when added to substances, but has a strong aftertaste and degrades easily during storage particularly when exposed to heat. Sucralose is highly stable, but can suppress the natural flavors of the food to which it added, and also has a heavy sweet aftertaste. Ace-K is also highly stable, but has a heavy taste and aftertaste, and particularly has a strong bitterness and astringency; therefore, Ace-K is often used in a combination with other high-intensity sweeteners.
The use of these high-intensity sweeteners in combination is one way to modify the qualities of the sweetness of the above-described high-intensity sweeteners (JP 2005-304440 A). Furthermore, the use of these high-intensity sweeteners in combination with other sweeteners such as trehalose and erythritol (JP 2002-51723 A), an α-glucosylated stevia extract (JP 2002-34501 A), and with a dietary fiber (JP 2004-41118 A) have been reported. However, at the present time, these combinations have not sufficiently satisfied consumers who are familiar with the sweetness of sugar or glucose fructose syrup.
The calcium receptor, which is also called the Calcium Sensing Receptor (CaSR), has 1,078 amino acids, and is classified into class C of the seven-transmembrane receptors (G protein-coupled receptor; GPCR). Cloning of the gene for the calcium receptor was reported in 1993 (Nature, 1993, Vol. 366(6455), pp. 575-580), and the calcium receptor is known to cause various cell responses via elevation of intracellular calcium levels, etc., when activated with calcium etc. The nucleotide sequence of the human calcium receptor is registered with GenBank Accession No. NM_000388, and is well conserved in animals.
The calcium receptor may act to promote or suppress biological functions. Therefore, at present, therapeutic agents are appropriately used in the treatment of diseases of the neurological, hepatic, cardiovascular, and digestive systems, and other diseases, depending on the pathological conditions. For example, the calcium receptor is able to detect increased blood calcium in the parathyroid, and then suppress the secretion of the parathyroid hormone (PTH) to correct the blood calcium level. Therefore, reduction of the blood calcium level is expected for a calcium receptor activator. It has actually been reported that when a calcium receptor activator is used to treat secondary hyperparathyroidism in a hemodialysis patient, it reduces the PTH level without increasing the calcium and phosphorus levels.
Since a functional analysis of the calcium receptor has been conducted mainly for calcium homeostasis, the applications have so far mainly focused on bone metabolic diseases in which calcium regulation is involved. However, it has become clear from the results of genetic expression analyses, etc., that the calcium receptor is widely distributed in living bodies other than in the parathyroid and kidney (J. Endocrinol., 2000, Vol. 165(2), pp. 173-177 and Eur. J. Pharmacol., 2002, Vol. 447(2-3), pp. 271-278), and the possibility that the calcium receptor is involved in various biological functions and perhaps even the causes of some diseases has been proposed. For example, there has been speculation that the calcium receptor is involved in the functions of the liver, heart, lung, gastrointestinal tract, lymphocytes and pancreas. It has also been confirmed that the calcium receptor is expressed in a wide range of tissues by analyzing RNAs extracted from rat tissues using RT-PCR. Therefore, the potential applications for activators and inhibitors of the calcium receptor are rapidly increasing.
Moreover, in addition to calcium, cations such as a gadolinium cation, basic peptides such as polyarginine, polyamine such as spermine, amino acids such as phenylalanine, and so forth have been reported as calcium receptor activators (Cell Calcium, 2004, Vol. 35(3), pp. 209-216).
It has also been reported that glutathione (γ-Glu-Cys-Gly), a low molecular weight peptide, is a CaSR activator (J. Biol. Chem., 2006, Vol. 281(13), pp. 8864-8870), but there are no reports of the possibility for the CaSR to be involved in taste reception.
However, it has not been reported that an amino acid or a peptide having a particular structure is useful as a calcium receptor activator. Although peptide derivatives with a sweet taste, such as aspartame, are known, it has not been previously reported that an amino acid or peptide that is able to activate a calcium receptor can improve the quality of the sweetness of a sweet substance. It should be noted that ANS9801 and neotame are described in U.S. Pat. No. 6,548,096 and International Publication NO. WO39979 pamphlet, respectively.